Emphasize that renovate only checks the main branch

.gitlab/issue_templates/new_app.md

@@ -61,7 +61,7 @@ Add app to following stages in `.gitlab-ci.yml`:
       /tmp/renovate.py --cluster-path flux2
       ```
 * [ ] Make sure that latest [renovate pipeline](https://open.greenhost.net/openappstack/renovate/-/pipelines)
-      checks for app updates
+      checks for app updates **after the new app is merged into the main branch**
 
 ## Documentation